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Abstract:

A wireless power transmission and charging system, and a communication
method of the wireless power transmission and charging system are
provided. In one embodiment, a resonance frequency control method of a
wireless power transmitter may include: generating communication power
used for communication in a plurality of target devices using a reference
resonance frequency; transmitting communication power to the plurality of
target devices; transmitting charging power to the plurality of target
devices; and adjusting the reference resonance frequency based on a
reflected wave of the charging power, the amount of power received by one
or more of the target devices, the amount of the charging power, the
transmission efficiency of the charging power, or any combination
thereof.

Claims:

1. A resonance frequency control method of a wireless power transmitter,
the method comprising: generating communication power used for
communication in a plurality of target devices using a reference
resonance frequency; transmitting communication power to the plurality of
target devices; transmitting charging power to the plurality of target
devices; and adjusting the reference resonance frequency based on a
reflected wave of the charging power, the amount of power received by one
or more of the target devices, the amount of the charging power, the
transmission efficiency of the charging power, or any combination
thereof.

2. The method of claim 1, wherein generating the communication power
comprises converting direct current (DC) voltage supplied to a power
amplifier to alternating current (AC) voltage using the reference
resonance frequency.

3. The method of claim 1, further comprising: transmitting a wake-up
request message to the plurality of target devices; receiving, from one
or more of the plurality of target devices, response messages
corresponding to the wake-up request message; and detecting the number
target devices based on the received response messages.

4. The method of claim 2, further comprising: generating the charging
power by adjusting a signal level of the DC voltage supplied to the power
amplifier based on the number of target devices.

5. The method of claim 3, wherein one or more of the response messages
corresponding to the wake-up request message comprises a product type of
a corresponding target device, manufacturer information of the
corresponding target device, a product model name of the corresponding
target device, a battery type of the corresponding target device, a
charging scheme of the corresponding target device, an impedance value of
a load of the corresponding target device, information about a
characteristic of a target resonator of the corresponding target device,
information about a used frequency band of the corresponding target
device, an amount of power to be used for the corresponding target
device, an intrinsic identifier of the corresponding target device,
product version information or standards information of the corresponding
target device, or any combination thereof.

6. The method of claim 4, wherein the generating of the charging power
comprises: determining the signal level of the DC voltage supplied to the
power amplifier based on the product type of the corresponding target
device, the manufacturer information of the corresponding target device,
the product model name of the corresponding target device, the battery
type of the corresponding target device, the charging scheme of the
corresponding target device, the impedance value of the load of the
corresponding target device, the information about the characteristic of
the target resonator of the corresponding target device, the information
about the used frequency band of the corresponding target device, the
amount of the power to be used for the corresponding target device, the
intrinsic identifier of the corresponding target device, the product
version information or standards information of the corresponding target
device, or any combination thereof.

7. The method of claim 1, wherein the adjusting of the reference
resonance frequency comprises: calculating a voltage standing wave ratio
(VSWR) based on the voltage level of the reflected wave, and the level of
an output voltage and a level of an output current of a source resonator;
determining a tracking frequency having the highest power transmission
efficiency among N predetermined tracking frequencies when the VSWR is
less than a predetermined reference value; and generating charging power
using the tracking frequency having the highest power transmission
efficiency.

8. The method of claim 7, wherein the determining of the tracking
frequency having the highest power transmission efficiency comprises:
performing the following operations a) through g) for one or more of the
N predetermined tracking frequencies, a) selecting one of the N
predetermined tracking frequencies based on a predetermined frequency
selection scheme; b) changing the reference resonance frequency to the
selected tracking frequency; c) transmitting the charging power; d)
transmitting, to the plurality of target devices, a command to request an
input voltage value and an input current value of a target device, or a
command to request a DC/DC output voltage value and a DC/DC output
current value of the target device; e) receiving, from each of the
plurality of target devices, an input voltage value and an input current
value of a rectification unit, or the DC/DC output voltage value and the
DC/DC output current value; f) calculating an amount of power received by
each of the plurality of target devices based on the input voltage value
and the input current value, or the DC/DC output voltage value and the
DC/DC output current value; and g) calculating the transmission
efficiency of the charging power based on an output voltage level and an
output current level of the source resonator, and the amount of the power
received by each of the plurality of target devices.

9. The method of claim 8, wherein the predetermined frequency selection
scheme in the operation a) corresponds to a scheme of selecting
frequencies in a sequential order, starting from a low frequency to a
high frequency among the N predetermined tracking frequencies, or a
scheme of selecting frequencies in a sequential order, starting from a
high frequency to a low frequency among the N predetermined tracking
frequencies.

10. The method of claim 8, wherein the predetermined frequency selection
scheme in the operation a) corresponds to a scheme of sequentially
selecting M predetermined tracking frequencies from the N predetermined
tracking frequencies, primarily performing the operations b) through g)
continuously for one or more of the M predetermined tracking frequencies,
and secondarily performing the operations b) through g) continuously for
each tracking frequency, excluding the M predetermined tracking
frequencies from the N predetermined tracking frequencies, M being less
than N.

11. The method of claim 8, wherein the predetermined frequency selection
scheme in the operation a) corresponds to a scheme of classifying the N
predetermined tracking frequencies into M groups, selecting one of the M
groups based on the number of the plurality of target devices, and
sequentially selecting tracking frequencies included in the selected
group, M being less than N.

12. A wireless power transmitter comprising: a power converter configured
to generate communication power used for communication, charging power
used for charging in a plurality of target devices, or both using a
reference resonance frequency; a source resonator configured to transmit,
to the plurality of target devices, the communication power, the charging
power, or both; and a control/communication unit configured to adjust the
reference resonance frequency based on a reflected wave of the charging
power, the amount of power received by one or more of the plurality of
target devices, the amount of the charging power, the transmission
efficiency of the charging power, or any combination thereof.

13. The wireless power transmitter of claim 12, wherein the power
converter is configured to generate the communication power, the charging
power, or both by converting direct current (DC) voltage supplied to a
power amplifier to alternating current (AC) voltage using the reference
resonance frequency.

14. The wireless power transmitter of claim 13, wherein the
control/communication unit is configured to adjust the signal level of
the DC voltage supplied to the power amplifier based on the number of the
plurality of target devices.

15. The wireless power transmitter of claim 14, wherein the
control/communication unit is configured to determine the signal level of
the DC voltage to be supplied to the power amplifier, based on a product
type of a corresponding target device, manufacturer information of the
corresponding target device, a product model name of the corresponding
target device, a battery type of the corresponding target device, a
charging scheme of the corresponding target device, an impedance value of
a load of the corresponding target device, information about a
characteristic of a target resonator of the corresponding target device,
information about a used frequency band of the corresponding target
device, an amount of power to be used for the corresponding target
device, an intrinsic identifier of the corresponding target device,
product version information or standards information of the corresponding
target device, or any combination thereof.

16. The wireless power transmitter of claim 12, wherein the
control/communication unit is configured to calculate a voltage standing
wave ratio (VSWR) based on a voltage level of the reflected wave, and a
level of an output voltage and a level of an output current of the source
resonator, to calculate a power transmission efficiency for one or more
of N predetermined tracking frequencies when the VSWR is less than a
predetermined value, to determine a tracking frequency having the highest
power transmission efficiency, among the N predetermined tracking
frequencies, and to change the reference resonance frequency to the
tracking frequency having the highest power transmission efficiency.

17. The wireless power transmitter of claim 16, wherein the
control/communication unit is configured to perform the following
operations a) through g) for one or more of the N predetermined tracking
frequencies in order to determine the tracking frequency having the
highest power transmission efficiency, a) selecting one of the N
predetermined tracking frequencies based on a predetermined frequency
selection scheme; b) changing the reference resonance frequency to the
selected tracking frequency; c) transmitting the charging power; d)
transmitting, to the plurality of target devices, a command to request an
input voltage value and an input current value of a target device, or a
command to request a DC/DC output voltage value and a DC/DC output
current value of the target device; e) receiving, from each of the
plurality of target devices, an input voltage value and an input current
value of a rectification unit, or the DC/DC output voltage value and the
DC/DC output current value; f) calculating an amount of power received by
each of the plurality of target devices, based on the input voltage value
and the input current value, or the DC/DC output voltage value and the
DC/DC output current value; and g) calculating a transmission efficiency
of the charging power, based on an output voltage level and an output
current level of the source resonator, and the amount of the power
received by each of the plurality of target devices.

18. The wireless power transmitter of claim 17, wherein the predetermined
frequency selection scheme in the operation a) corresponds to a scheme of
selecting frequencies in a sequential order, starting from a low
frequency to a high frequency among the N predetermined tracking
frequencies, or a scheme of selecting frequencies in a sequential order,
starting from a high frequency to a low frequency among the N
predetermined tracking frequencies.

19. The wireless power transmitter of claim 17, wherein the predetermined
frequency selection scheme in the operation a) corresponds to a scheme of
sequentially selecting M predetermined tracking frequencies from the N
predetermined tracking frequencies, primarily performing the operations
b) through g) continuously for each of the M predetermined tracking
frequencies, and secondarily performing the operations b) through g)
continuously for each tracking frequency, excluding the M predetermined
tracking frequencies from the N predetermined tracking frequencies, M
being less than N.

20. The wireless power transmitter of claim 17, wherein the predetermined
frequency selection scheme in the operation a) corresponds to a scheme of
classifying the N predetermined tracking frequencies into M groups,
selecting one of the M groups based on the number of the plurality of
target devices, and sequentially selecting tracking frequencies included
in the selected group, M being less than N.

21. A wireless power receiver comprising: a target resonator configured
to receive power from a source resonator; and a control/communication
unit configured to: detect the amount of power received by the target
resonator, and transmit, to the wireless power transmitter, information
about the amount of the power received by the target resonator.

22. The wireless power receiver of claim 21, wherein the
control/communication unit configured to receive a wake-up request
message from the wireless power transmitter.

23. The wireless power receiver of claim 21, further comprising: a
rectification unit configured to generate a direct current (DC) signal by
rectifying an alternating current (AC) signal of the power received by
the target resonator; and a DC/DC converter configured to supply voltage
of a predetermined level to a load by adjusting a level of the DC signal.

24. The wireless power receiver of claim 21, wherein the
control/communication unit is configured to transmit, to the wireless
power transmitter, a response message comprising a product type of a
corresponding target device, manufacturer information of the
corresponding target device, a product model name of the corresponding
target device, a battery type of the corresponding target device, a
charging scheme of the corresponding target device, an impedance value of
a load of the corresponding target device, information about a
characteristic of a target resonator of the corresponding target device,
information about a used frequency band of the corresponding target
device, an amount of power to be used for the corresponding target
device, an intrinsic identifier of the corresponding target device,
product version information or standards information of the corresponding
target device, or any combination thereof.

25. The wireless power receiver of claim 21, wherein the information
about the amount of the power received by the target resonator
corresponds to an input voltage value and an input current value of the
rectification unit, an output voltage value and an output current value
of the rectification unit, or a DC/DC output voltage value and a DC/DC
output current value.

26. A power receiving method of a wireless power receiver, the method
comprising: receiving communication power used for communication, that is
generated using a reference resonance frequency, from a wireless power
transmitter; receiving first charging power from the wireless power
transmitter; and receiving second charging power that is generated using
an adjusted reference resonance frequency after the reference resonance
frequency has been adjusted in the wireless power transmitter.

27. The method of claim 26, further comprising: receiving a wake-up
request message from the wireless power transmitter; and transmitting, to
the wireless power transmitter, a response message corresponding to the
wake-up request message.

28. The method of claim 26, wherein the first charging power is generated
by adjusting a signal level of a direct current (DC) voltage to be
supplied to a power amplifier of the wireless power transmitter.

29. The method of claim 26, wherein the reference resonance frequency is
adjusted based on a reflected wave of the first charging power, an amount
of the first charging power, or a transmission efficiency of the first
charging power.

30. The method of claim 26, wherein the response message corresponding to
the wake-up request message comprises a product type of a corresponding
target device, manufacturer information of the corresponding target
device, a product model name of the corresponding target device, a
battery type of the corresponding target device, a charging scheme of the
corresponding target device, an impedance value of a load of the
corresponding target device, information about a characteristic of a
target resonator of the corresponding target device, information about a
used frequency band of the corresponding target device, an amount of
power to be used for the corresponding target device, an intrinsic
identifier of the corresponding target device, or product version
information or standards information of the corresponding target device.

31. The method of claim 26, wherein the adjusted reference resonance
frequency corresponds to a tracking frequency having the highest power
transmission efficiency, among N predetermined tracking frequencies.

32. The method of claim 31, wherein the tracking frequency having the
highest power transmission efficiency is determined by performing the
following operations a) through c) for each of the N predetermined
tracking frequencies, a) receiving the second charging power; b)
receiving, from the wireless power transmitter, a command to request an
input voltage value and an input current value of a target device, or a
command to request a DC/DC output voltage value and a DC/DC output
current value of the target device; and c) transmitting, to the wireless
power transmitter, an input voltage value and an input current value of a
rectification unit, or the DC/DC output voltage value and the DC/DC
output current value.

33. A resonance frequency control method of a wireless power transmitter,
the method comprising: adjusting a reference resonance frequency of the
wireless power transmitter based on a reflected wave of a charging power,
the amount of power received by one or more of target devices, the amount
of the charging power, the transmission efficiency of the charging power,
or any combination thereof.

Description:

CROSS-REFERENCE TO RELATED APPLICATION(S)

[0001] This application claims the benefit under 35 U.S.C. §119(a) of
Korean Patent Application No. 10-2011-0044679, filed on May 12, 2011, in
the Korean Intellectual Property Office, the entire disclosure of which
is incorporated herein by reference for all purposes.

BACKGROUND

[0002] 1. Field

[0003] The following disclosure relates to wireless power transmission and
charging.

[0004] 2. Description of Related Art

[0005] Wireless power refers to energy that is transferred from a wireless
power transmitter to a wireless power receiver, for example, using a
magnetic coupling. The wireless power receiver may be used to charge a
battery using the received energy. A typical wireless power transmission
and charging system includes a source device to wirelessly transmit power
and a target device to wirelessly receive the power. The source device
may be referred to as a wireless power transmitter, and the target device
may be referred to as a wireless power receiver.

[0006] The source device includes a source resonator, and the target
device includes a target resonator, with a magnetic coupling or resonance
coupling provided between the source resonator and the target resonator.
The source device and the target device may perform communication to
transmit and receive control information and state information.

SUMMARY

[0007] According to a general aspect, a resonance frequency control method
of a wireless power transmitter may include: generating communication
power used for communication in a plurality of target devices using a
reference resonance frequency; transmitting communication power to the
plurality of target devices; transmitting charging power to the plurality
of target devices; and adjusting the reference resonance frequency based
on a reflected wave of the charging power, the amount of power received
by one or more of the target devices, the amount of the charging power,
the transmission efficiency of the charging power, or any combination
thereof.

[0008] The generating of the communication power may include converting
direct current (DC) voltage supplied to a power amplifier to alternating
current (AC) voltage using the reference resonance frequency.

[0009] The method may further include: transmitting a wake-up request
message to the plurality of target devices; receiving, from one or more
of the plurality of target devices, response messages corresponding to
the wake-up request message; and detecting the number target devices
based on the received response messages.

[0010] The method may further include: generating the charging power by
adjusting a signal level of the DC voltage supplied to the power
amplifier based on the number of target devices.

[0011] One or more of the response messages corresponding to the wake-up
request message may include a product type of a corresponding target
device, manufacturer information of the corresponding target device, a
product model name of the corresponding target device, a battery type of
the corresponding target device, a charging scheme of the corresponding
target device, an impedance value of a load of the corresponding target
device, information about a characteristic of a target resonator of the
corresponding target device, information about a used frequency band of
the corresponding target device, an amount of power to be used for the
corresponding target device, an intrinsic identifier of the corresponding
target device, product version information or standards information of
the corresponding target device, or any combination thereof.

[0012] The generating of the charging power may include: determining the
signal level of the DC voltage supplied to the power amplifier based on
the product type of the corresponding target device, the manufacturer
information of the corresponding target device, the product model name of
the corresponding target device, the battery type of the corresponding
target device, the charging scheme of the corresponding target device,
the impedance value of the load of the corresponding target device, the
information about the characteristic of the target resonator of the
corresponding target device, the information about the used frequency
band of the corresponding target device, the amount of the power to be
used for the corresponding target device, the intrinsic identifier of the
corresponding target device, the product version information or standards
information of the corresponding target device, or any combination
thereof.

[0013] The adjusting of the reference resonance frequency may include:
calculating a voltage standing wave ratio (VSWR) based on the voltage
level of the reflected wave, and the level of an output voltage and a
level of an output current of a source resonator; determining a tracking
frequency having the highest power transmission efficiency among N
predetermined tracking frequencies when the VSWR is less than a
predetermined reference value; and generating charging power using the
tracking frequency having the highest power transmission efficiency.

[0014] The determining of the tracking frequency having the highest power
transmission efficiency may include: performing the following operations
a) through g) for one or more of the N predetermined tracking
frequencies, a) selecting one of the N predetermined tracking frequencies
based on a predetermined frequency selection scheme; b) changing the
reference resonance frequency to the selected tracking frequency;
c)transmitting the charging power; d) transmitting, to the plurality of
target devices, a command to request an input voltage value and an input
current value of a target device, or a command to request a DC/DC output
voltage value and a DC/DC output current value of the target device; e)
receiving, from each of the plurality of target devices, an input voltage
value and an input current value of a rectification unit, or the DC/DC
output voltage value and the DC/DC output current value; f) calculating
an amount of power received by each of the plurality of target devices
based on the input voltage value and the input current value, or the
DC/DC output voltage value and the DC/DC output current value; and g)
calculating the transmission efficiency of the charging power based on an
output voltage level and an output current level of the source resonator,
and the amount of the power received by each of the plurality of target
devices.

[0015] The predetermined frequency selection scheme in the operation a)
may correspond to a scheme of selecting frequencies in a sequential
order, starting from a low frequency to a high frequency among the N
predetermined tracking frequencies, or a scheme of selecting frequencies
in a sequential order, starting from a high frequency to a low frequency
among the N predetermined tracking frequencies.

[0016] The predetermined frequency selection scheme in the operation a)
may correspond to a scheme of sequentially selecting M predetermined
tracking frequencies from the N predetermined tracking frequencies,
primarily performing the operations b) through g) continuously for one or
more of the M predetermined tracking frequencies, and secondarily
performing the operations b) through g) continuously for each tracking
frequency, excluding the M predetermined tracking frequencies from the N
predetermined tracking frequencies, M being less than N.

[0017] The predetermined frequency selection scheme in the operation a)
may correspond to a scheme of classifying the N predetermined tracking
frequencies into M groups, selecting one of the M groups based on the
number of the plurality of target devices, and sequentially selecting
tracking frequencies included in the selected group, M being less than N.

[0018] According to another general aspect, a wireless power transmitter
may include: a power converter configured to generate communication power
used for communication, charging power used for charging in a plurality
of target devices, or both using a reference resonance frequency; a
source resonator configured to transmit, to the plurality of target
devices, the communication power, the charging power, or both; and a
control/communication unit configured to adjust the reference resonance
frequency based on a reflected wave of the charging power, the amount of
power received by one or more of the plurality of target devices, the
amount of the charging power, the transmission efficiency of the charging
power, or any combination thereof.

[0019] The power converter may be configured to generate the communication
power, the charging power, or both by converting direct current (DC)
voltage supplied to a power amplifier to alternating current (AC) voltage
using the reference resonance frequency.

[0020] The control/communication unit may be configured to adjust the
signal level of the DC voltage supplied to the power amplifier based on
the number of the plurality of target devices.

[0021] The control/communication unit may be configured to determine the
signal level of the DC voltage to be supplied to the power amplifier,
based on a product type of a corresponding target device, manufacturer
information of the corresponding target device, a product model name of
the corresponding target device, a battery type of the corresponding
target device, a charging scheme of the corresponding target device, an
impedance value of a load of the corresponding target device, information
about a characteristic of a target resonator of the corresponding target
device, information about a used frequency band of the corresponding
target device, an amount of power to be used for the corresponding target
device, an intrinsic identifier of the corresponding target device,
product version information or standards information of the corresponding
target device, or any combination thereof.

[0022] The control/communication unit may be configured to calculate a
voltage standing wave ratio (VSWR) based on a voltage level of the
reflected wave, and a level of an output voltage and a level of an output
current of the source resonator, to calculate the power transmission
efficiency for one or more of N predetermined tracking frequencies when
the VSWR is less than a predetermined value, to determine a tracking
frequency having the highest power transmission efficiency, among the N
predetermined tracking frequencies, and to change the reference resonance
frequency to the tracking frequency having the highest power transmission
efficiency.

[0023] The control/communication unit may be configured to perform the
following operations a) through g) for one or more of the N predetermined
tracking frequencies in order to determine the tracking frequency having
the highest power transmission efficiency, a) selecting one of the N
predetermined tracking frequencies based on a predetermined frequency
selection scheme; b) changing the reference resonance frequency to the
selected tracking frequency; c) transmitting the charging power; d)
transmitting, to the plurality of target devices, a command to request an
input voltage value and an input current value of a target device, or a
command to request a DC/DC output voltage value and a DC/DC output
current value of the target device; e) receiving, from each of the
plurality of target devices, an input voltage value and an input current
value of a rectification unit, or the DC/DC output voltage value and the
DC/DC output current value; f) calculating an amount of power received by
each of the plurality of target devices, based on the input voltage value
and the input current value, or the DC/DC output voltage value and the
DC/DC output current value; and g) calculating a transmission efficiency
of the charging power, based on an output voltage level and an output
current level of the source resonator, and the amount of the power
received by each of the plurality of target devices.

[0024] The predetermined frequency selection scheme in the operation a)
may correspond to a scheme of selecting frequencies in a sequential
order, starting from a low frequency to a high frequency among the N
predetermined tracking frequencies, or a scheme of selecting frequencies
in a sequential order, starting from a high frequency to a low frequency
among the N predetermined tracking frequencies.

[0025] The predetermined frequency selection scheme in the operation a)
may correspond to a scheme of sequentially selecting M predetermined
tracking frequencies from the N predetermined tracking frequencies,
primarily performing the operations b) through g) continuously for each
of the M predetermined tracking frequencies, and secondarily performing
the operations b) through g) continuously for each tracking frequency,
excluding the M predetermined tracking frequencies from the N
predetermined tracking frequencies, M being less than N.

[0026] The predetermined frequency selection scheme in the operation a)
may correspond to a scheme of classifying the N predetermined tracking
frequencies into M groups, selecting one of the M groups based on the
number of the plurality of target devices, and sequentially selecting
tracking frequencies included in the selected group, M being less than N.

[0027] According to yet another general aspect, a wireless power receiver
may include: a target resonator configured to receive power from a source
resonator; and a control/communication unit configured to: detect the
amount of power received by the target resonator, and transmit, to the
wireless power transmitter, information about the amount of the power
received by the target resonator.

[0028] The control/communication unit may be configured to receive a
wake-up request message from the wireless power transmitter.

[0029] The wireless power receiver may further include: a rectification
unit configured to generate a direct current (DC) signal by rectifying an
alternating current (AC) signal of the power received by the target
resonator; and a DC/DC converter configured to supply voltage of a
predetermined level to a load by adjusting a level of the DC signal.

[0030] The control/communication unit may be configured to transmit, to
the wireless power transmitter, a response message comprising a product
type of a corresponding target device, manufacturer information of the
corresponding target device, a product model name of the corresponding
target device, a battery type of the corresponding target device, a
charging scheme of the corresponding target device, an impedance value of
a load of the corresponding target device, information about a
characteristic of a target resonator of the corresponding target device,
information about a used frequency band of the corresponding target
device, an amount of power to be used for the corresponding target
device, an intrinsic identifier of the corresponding target device,
product version information or standards information of the corresponding
target device, or any combination thereof.

[0031] The information about the amount of the power received by the
target resonator may correspond to an input voltage value and an input
current value of the rectification unit, an output voltage value and an
output current value of the rectification unit, or a DC/DC output voltage
value and a DC/DC output current value.

[0032] According to a further general aspect, a power receiving method of
a wireless power receiver may include: receiving communication power that
is generated using a reference resonance frequency, from a wireless power
transmitter; receiving first charging power from the wireless power
transmitter; and receiving second charging power that is generated using
an adjusted reference resonance frequency after the reference resonance
frequency has been adjusted in the wireless power transmitter.

[0033] The method may further include: receiving a wake-up request message
from the wireless power transmitter; and transmitting, to the wireless
power transmitter, a response message corresponding to the wake-up
request message.

[0034] The first charging power may be generated by adjusting a signal
level of a direct current (DC) voltage to be supplied to a power
amplifier of the wireless power transmitter.

[0035] The reference resonance frequency may be adjusted based on a
reflected wave of the first charging power, an amount of the first
charging power, or a transmission efficiency of the first charging power.

[0036] The response message corresponding to the wake-up request message
may include: a product type of a corresponding target device,
manufacturer information of the corresponding target device, a product
model name of the corresponding target device, a battery type of the
corresponding target device, a charging scheme of the corresponding
target device, an impedance value of a load of the corresponding target
device, information about a characteristic of a target resonator of the
corresponding target device, information about a used frequency band of
the corresponding target device, an amount of power to be used for the
corresponding target device, an intrinsic identifier of the corresponding
target device, or product version information or standards information of
the corresponding target device.

[0037] The adjusted reference resonance frequency may correspond to a
tracking frequency having the highest power transmission efficiency,
among N predetermined tracking frequencies.

[0038] The tracking frequency having the highest power transmission
efficiency is determined by performing the following operations a)
through c) for one or more of the N predetermined tracking frequencies,
a) receiving the second charging power; b) receiving, from the wireless
power transmitter, a command to request an input voltage value and an
input current value of a target device, or a command to request a DC/DC
output voltage value and a DC/DC output current value of the target
device; and c) transmitting, to the wireless power transmitter, an input
voltage value and an input current value of a rectification unit, or the
DC/DC output voltage value and the DC/DC output current value.

[0039] According to an even further general aspect, a resonance frequency
control method of a wireless power transmitter may include: adjusting a
reference resonance frequency of the wireless power transmitter based on
a reflected wave of a charging power, the amount of power received by one
or more of target devices, the amount of the charging power, the
transmission efficiency of the charging power, or any combination
thereof.

[0040] Other features and aspects will be apparent from the following
detailed description, the drawings, and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0041] FIG. 1 is a diagram illustrating a wireless power transmission and
charging system.

[0042]FIG. 2 is a diagram illustrating one configuration of a power
converter illustrated in FIG. 1.

[0043]FIG. 3 is a diagram illustrating an operation environment of a
wireless power transmission and charging system.

[0044]FIG. 4 is a diagram illustrating a resonance frequency control
method.

[0045] FIG. 5 is a diagram illustrating an operation of adjusting a
resonance frequency illustrated in FIG. 4.

[0046] FIG. 6 is a diagram illustrating a method of selecting a tracking
frequency having the highest power transmission efficiency illustrated in
FIG. 5.

[0051] Throughout the drawings and the detailed description, unless
otherwise described, the same drawing reference numerals should be
understood to refer to the same elements, features, and structures. The
relative size and depiction of these elements may be exaggerated for
clarity, illustration, and convenience.

DETAILED DESCRIPTION

[0052] The following detailed description is provided to assist the reader
in gaining a comprehensive understanding of the methods, apparatuses
and/or systems described herein. Accordingly, various changes,
modifications, and equivalents of the systems, apparatuses and/or methods
described herein may be suggested to those of ordinary skill in the art.
The progression of processing steps and/or operations described is an
example; however, the sequence of and/or operations is not limited to
that set forth herein and may be changed as is known in the art, with the
exception of steps and/or operations necessarily occurring in a certain
order. Also, descriptions of well-known functions and constructions may
be omitted for increased clarity and conciseness.

[0054] As shown, the wireless power transmission and charging system
includes a source device 110, and a target device 120.

[0055] The source device 110 includes an alternating current-to-direct
current (AC/DC) converter 111, a power detector 113, a power converter
114, a control and communication (control/communication) unit 115, and a
source resonator 116.

[0057] The AC/DC converter 111 may be configured to generate a DC voltage,
for example, by rectifying an AC voltage (e.g., in a band of tens of
hertz (Hz)) output from a power supply 112. The AC/DC converter 111 may
be configured to output a DC voltage of a predetermined level, or may
adjust an output level of a DC voltage based on the control of the
control/communication unit 115.

[0058] The power detector 113 may be configured to detect an output
current and an output voltage of the AC/DC converter 111, and may
transfer, to the control/communication unit 115, information on the
detected current and the detected voltage. Additionally, the power
detector 113 may detect an input current and an input voltage of the
power converter 114.

[0059] The power converter 114 may generate power by converting DC voltage
of a predetermined level to AC voltage, using a switching pulse signal
(e.g., in a band of a few megahertz (MHz) to tens of MHz). For example,
the power converter 114 may generate a communication power used for
communication or a charging power used for charging in a plurality of
target devices by converting DC voltage supplied to a power amplifier to
AC voltage using a reference resonance frequency FRef. The
communication power and the charging power will be described later with
reference to FIG. 4.

[0060] The reference resonance frequency may refer to a resonance
frequency used by the source device 110. Also, the tracking frequency may
refer to a resonance frequency adjusted based on a predetermined scheme.

[0061] The control/communication unit 115 may detect a reflected wave of
the communication power and/or a reflected wave of the charging power,
and may detect mismatching between the target resonator 121 and the
source resonator 116 based on the detected reflected wave. The
control/communication unit 115 may detect the mismatching by detecting an
envelope of the reflected wave, or by detecting an amount of power of the
reflected wave. The control/communication unit 115 may calculate a
voltage standing wave ratio (VSWR), based on a voltage level of the
reflected wave, and a level of an output voltage of the source resonator
116 or the power converter 114. When the VSWR is less than a
predetermined value, the control/communication unit 115 may determine
that the mismatching is detected. For example, the control/communication
unit 115 may calculate a power transmission efficiency of each of N
predetermined tracking frequencies, determine a tracking frequency
FBest having the best or highest power transmission efficiency,
among the N predetermined tracking frequencies, and change the reference
resonance frequency FRef to the tracking frequency FBest.

[0062] Also, the control/communication unit 115 may control a frequency of
a switching pulse signal. Under the control of the control/communication
unit 115, the frequency of the switching pulse signal may be determined.
By controlling the power converter 114, the control/communication unit
115 may generate a modulation signal to be transmitted to the target
device 120. In other words, the control/communication unit 115 may
transmit various messages to the target device 120 via in-band
communications. Additionally, the control/communication unit 115 may
detect a reflected wave, and may demodulate a signal received from the
target device 120 through an envelope of the reflected wave.

[0063] The term "in-band" communication(s), as used herein, means
communication(s) in which information (such as, for example, control
information, data and/or metadata) is transmitted in the same frequency
band, and/or on the same channel, as used for power transmission.
According to one or more embodiments, the frequency may be a resonance
frequency. And, the term "out-band" communication(s), as used herein,
means communication(s) in which information (such as, for example,
control information, data and/or metadata) is transmitted in a separate
frequency band and/or using a separate or dedicated channel, than used
for power transmission.

[0064] The control/communication unit 115 may generate a modulation signal
for in-band communication, using various schemes. To generate a
modulation signal, the control/communication unit 115 may turn on or off
a switching pulse signal, or may perform delta-sigma modulation.
Additionally, the control/communication unit 115 may generate a
pulse-width modulation (PWM) signal with a predetermined envelope.

[0065] The control/communication unit 115 may perform out-band
communication using a communication channel. The control/communication
unit 115 may include a communication module, such as one configured to
process ZigBee, Wi-Fi, Wi-Max, Bluetooth, and the like communication
protocols. The control/communication unit 115 may transmit or receive
data to or from the target device 120 via the out-band communication.

[0066] The source resonator 116 may transfer electromagnetic energy to the
target resonator 121. For example, the source resonator 116 may transfer,
to the target device 120, the communication power, the charging power, or
both using a magnetic coupling with the target resonator 121.

[0067] The target resonator 121 may receive the electromagnetic energy
from the source resonator 116. For example, the target resonator 121 may
receive, from the source device 110, the communication power or the
charging power using a magnetic coupling with the source resonator 116.
Additionally, the target resonator 121 may receive various messages from
the source device 110 via the in-band communication.

[0068] The rectification unit 122 may generate a DC voltage by rectifying
an AC voltage. The rectification unit 122 may rectify an AC voltage
received by the target resonator 121.

[0069] The DC/DC converter 123 may adjust a level of the DC voltage output
from the rectification unit 122, based on a capacity of the charging unit
125. For example, the DC/DC converter 123 may adjust, to 3 to 10 V, the
level of the DC voltage output from the rectification unit 122.

[0070] The switch unit 124 may be turned ON or OFF, under the control of
the control/communication unit 126. When the switch unit 124 is turned
OFF, the control/communication unit 115 of the source device 110 may
detect a reflected wave. And, when the switch unit 124 is turned OFF, the
magnetic coupling between the source resonator 116 and the target
resonator 121 may be eliminated.

[0071] The charging unit 125 may include at least one battery. The
charging unit 125 may charge the at least one battery using a DC voltage
output from the DC/DC converter 123.

[0072] The control/communication unit 126 may perform in-band
communication for transmitting or receiving data using a resonance
frequency. The control/communication unit 126 may demodulate a received
signal by detecting a signal between the target resonator 121 and the
rectification unit 122, or by detecting an output signal of the
rectification unit 122. For instance, the control/communication unit 126
may demodulate a message received via the in-band communication.

[0073] Additionally, the control/communication unit 126 may adjust an
impedance of the target resonator 121, to modulate a signal to be
transmitted to the source device 110. The control/communication unit 126
may modulate the signal to be transmitted to the source device 110, by
turning ON or OFF the switch unit 124. For example, the
control/communication unit 126 may increase the impedance of the target
resonator 121, so that a reflected wave may be detected by the
control/communication unit 115 of the source device 110. Depending on
whether the reflected wave is detected, the control/communication unit
115 of the source device 110 may detect a binary number (e.g., "0" or
"1").

[0074] The control/communication unit 126 may transmit, to the wireless
power transmitter, a response message including a product type of a
corresponding target device, manufacturer information of the
corresponding target device, a product model name of the corresponding
target device, a battery type of the corresponding target device, a
charging scheme of the corresponding target device, an impedance value of
a load of the corresponding target device, information about a
characteristic of a target resonator of the corresponding target device,
information about a used frequency band of the corresponding target
device, an amount of power to be used for the corresponding target
device, an intrinsic identifier of the corresponding target device,
product version information or standards information of the corresponding
target device, or any combination thereof.

[0075] The control/communication unit 126 may also perform an out-band
communication using a communication channel. The control/communication
unit 126 may include a communication module, such as one configured to
process ZigBee, Wi-Fi, Wi-Max, Bluetooth, and/or the like communications.
The control/communication unit 126 may transmit or receive data to or
from the source device 110 via the out-band communication.

[0076] The control/communication unit 126 may receive a wake-up request
message from the wireless power transmitter, detect an amount of power
received by the target resonator, and transmit, to the wireless power
transmitter, information about the amount of the power received by the
target resonator. The information about the amount of the power received
by the target resonator may correspond to an input voltage value and an
input current value of the rectification unit 122, an output voltage
value and an output current value of the rectification unit 122, or an
output voltage value and an output current value of the DC/DC converter
123.

[0077] The control/communication unit 115 may set a resonance bandwidth of
the source resonator 116. Based on the set resonance bandwidth of the
source resonator 116, a Q-factor (Qs) of the source 116 may be
determined.

[0078] The control/communication unit 126 may set a resonance bandwidth of
the target resonator 116. Based on the set resonance bandwidth of the
target resonator 116, a Q-factor of the target resonator 121 may be
determined. For instance, the resonance bandwidth of the source resonator
116 may be wider or narrower than the resonance bandwidth of the target
resonator 121. By using communications, the source device 110 and the
target device 120 may share information regarding each of the resonance
bandwidths of the source resonator 116 and the target resonator 121. When
a power higher than a reference value is requested from the target device
120, the Q-factor (Qs) of the source resonator 116 may be set to a value
greater than 100. When a power lower than the reference value is
requested from the target device 120, the Q-factor (Qs) of the source
resonator 116 may be set to a value less than 100.

[0079] In a resonance-based wireless power transmission, a resonance
bandwidth may be an importance factor. When Qt indicates a Q-factor based
on a change in a distance between the source resonator 116 and the target
resonator 121, a change in resonance impedance, impedance-mismatching, a
reflected signal, and the like, Qt may be in inverse proportion to a
resonance bandwidth, as given in Equation 1.

[0082] In Equation 2, K denotes a coupling coefficient regarding energy
coupling between the source resonator 116 and the target resonator 121,
ΓS denotes a reflection coefficient of the source resonator
116, ΓD denotes a reflection coefficient of the target
resonator 121, ω0 denotes a resonance frequency, M denotes a
mutual inductance between the source resonator 116 and the target
resonator 121, RS denotes an impedance of the source resonator 116,
RD denotes an impedance of the target resonator 121, QS denotes
a Q-factor of the source resonator 116, QD denotes a Q-factor of the
target resonator 121, and QK denotes a Q-factor regarding energy
coupling between the source resonator 116 and the target resonator 121.

[0083] Referring to Equation 2, the Q-factor may be highly associated with
an efficiency of the wireless power transmission.

[0084] Accordingly, the Q-factor may be set to a great value in order to
increase the efficiency of the wireless power transmission. When QS
and QD are respectively set to a significantly great value, the
efficiency of the wireless power transmission may be reduced based on a
change in the coupling coefficient K regarding the energy coupling, a
change in a distance between the source resonator 116 and the target
resonator 121, a change in a resonance impedance, impedance mismatching,
and the like.

[0085] When each of the resonance bandwidths of the source resonator 116
and the target resonator 121 is set to be too narrow in order to increase
the efficiency of the wireless power transmission, the impedance
mismatching and the like may easily occur due to insignificant external
influences. In consideration of the impedance mismatching, Equation 1 may
be expressed by Equation 3.

Δ f f 0 = V S W R - 1
Qt V S W R [ Equation 3 ]
##EQU00003##

[0086] When the resonance bandwidth between the source resonator 116 and
the target resonator 121, or a bandwidth of a impedance-matching
frequency is maintained to be unbalanced, the efficiency of the wireless
power transmission may be reduced based on a change in the coupling
coefficient K, a change in a distance between the source resonator 116
and the target resonator 121, a change in a resonance impedance,
impedance mismatching, and the like. According to Equation 1 through
Equation 3, when the resonance bandwidth between the source resonator 116
and the target resonator 121, or the bandwidth of impedance-matching
frequency remains unbalanced, the Q-factor of the source resonator 116
and the Q-factor of the target resonator 121 may remain unbalanced.

[0087]FIG. 2 illustrates one configuration of the power converter 114
illustrated in FIG. 1.

[0088] Referring to FIG. 2, the power converter 114 includes a switching
pulse signal generation unit 210, and a power amplifier 220.

[0089] The switching pulse signal generator 210 may generate a switching
pulse signal, for example, in a band of a few MHz to tens of MHz. The
frequency of the generated switching pulse signal may be determined
according to the control of the control/communication unit 115. For
example, when a reference resonance frequency FRef of the source
resonator 116 corresponds to 13.56 MHz or 5.78 MHz, the
control/communication unit 115 may control the switching pulse signal
generator 210 to generate a switching pulse signal having a frequency
corresponding to 13.56 MHz or 5.78 MHz. The switching pulse signal
generator 210 may include one or more capacitors, and a switch. The
switching pulse signal generator 210 may adjust the frequency of the
switching pulse signal by switching the one or more capacitors.

[0090] The power amplifier 220 may generate an AC power using a switching
pulse signal output from a resonance frequency generator. For example,
the power amplifier 220 may generate a communication power used for
communication or a charging power used for charging, by switching an
input voltage of the power amplifier 220 of FIG. 2 based on the switching
pulse signal.

[0091] The control/communication unit 115 may adjust a signal level of the
input voltage of the power amplifier 220 based on a number of the
plurality of target devices. Additionally, the control/communication unit
115 may adjust the reference resonance frequency FRef based on a
reflected wave of the charging power, an amount of power received by each
of the plurality of target devices, an amount of the charging power, or a
transmission efficiency of the charging power.

[0092]FIG. 3 illustrates an operation environment of a wireless power
transmission and charging system.

[0093] Referring to FIG. 3, a source device 310 may wirelessly transmit
energy to a plurality of target devices 321, 323, and 325 simultaneously.
According to a resonance-based wireless power transmission scheme, the
single source device 310 may simultaneously charge the plurality of
target devices 321, 323, and 325.

[0094] According to the resonance-based wireless power transmission
scheme, the source device 310 and the plurality of target devices 321,
323, and 325 may transmit and receive data via an in-band communication,
or an out-band communication.

[0095] In an in-band communication scheme, power and a signal may be
transmitted within a coupling area between a source resonator and a
target resonator. Unlike an out-band communication scheme, the in-band
communication scheme may cause a small amount of interference in
peripheral devices, in certain instances. The out-band communication may
use a communication channel, such as a ZigBee channel, Wi-Fi channel,
Wi-Max channel, a Bluetooth channel, and/or the like. In the in-band
communication, data may be transmitted using a power transmitting
channel.

[0097] As illustrated in FIG. 4, a source device, a target device 1, and a
target device 2 may transmit and receive data via an in-band
communication. Also, the source device, the target device 1, and the
target device 2 may transmit and receive data via an out-band
communication.

[0098] Referring to FIG. 4, in operation 410, the source device is
operated in a standby mode when a target is not detected. When the target
device 1 and the target device 2 are detected in the standby mode, the
source device may generate communication power used in the target device.
The source device may generate the communication power used in a
plurality of target devices by converting DC voltage supplied to the
power amplifier 220 of FIG. 2 to AC voltage using a reference resonance
frequency FRef. For instance, the source device may transmit a test
signal at predetermined periods, or may detect the target device 1 or the
target device 2 using a pressure sensor. When the target device 1 is
disposed on the source device, the source device may detect the target
device 1 using the pressure sensor included in the source device. Also,
the source device may be switched from the standby mode to an access mode
by a predetermined control signal. The access mode may refer to a mode in
which operations in 420 and 430 of FIG. 4 may be performed.

[0099] In operation 420, the source device transmits the communication
power to the target device 1 or the target device 2, for instance, using
a magnetic coupling. The source device may generate the communication
power used in the target device, by converting DC voltage to be supplied
to the power amplifier 220 to AC voltage using a reference resonance
frequency FRef. The communication power may refer to energy used for
activating a communication module and a processor of the target device.
The communication power may be transmitted during a predetermined time in
a form of a constant wave (CW). The target device 1 and the target device
2 may receive power requested for operating the communication module and
the processor, by receiving the communication power.

[0100] In operation 430, the source device wakes up the target device, or
assigns a virtual identifier to the target device. Similarly, the target
device may receive a wake-up request message from the source device, and
may be assigned the virtual identifier. For instance, the target device 1
and the target device 1 and the target device 2 may activate a
communication and control function by receiving the wake-up request
message, and may be assigned the virtual identifier from the source
device.

[0101] Operation 430 includes operation 431 in which the source device
transmits a wake-up request message to the target device 1 and the target
device 2, operation 433 in which the source device receives an
acknowledge (ACK) message from the target device 1, and operation 435 in
which the source device receives an ACK message from the target device 2.
In operation 431, the source device may transmit a wake-up request
message to a plurality of target devices. In operations 433 and 435, the
source device may receive response messages corresponding to the wake-up
request message from each of the plurality of target devices. The source
device may detect a number of the plurality of target devices based on
the received response messages. In some instances, a response message and
an ACK message may refer to the same message.

[0102] For example, the ACK messages may include identifier information of
each of the target device 1 and the target device 2. The identifier
information included in the ACK message may correspond to an intrinsic
identifier of each of the target device 1 and the target device 2. Also,
one or more of the response messages corresponding to the wake-up request
message may include a product type of a corresponding target device,
manufacturer information of the corresponding target device, a product
model name of the corresponding target device, a battery type of the
corresponding target device, a charging scheme of the corresponding
target device, an impedance value of a load of the corresponding target
device, to information about a characteristic of a target resonator of
the corresponding target device, information about a used frequency band
of the corresponding target device, an amount of power to be used for the
corresponding target device, an intrinsic identifier of the corresponding
target device, product version information or standards information of
the corresponding target device, or any combination thereof.

[0103] Operation 430 further includes operation 437 in which a virtual
identifier is assigned. The virtual identifier may be used instead of the
intrinsic identifier of each of the target device I and the target device
2. The virtual identifier may correspond to a temporary identifier that
may be used for charging. For example, the virtual identifier may be
assigned using numbers from 1 to 8 based on a sequence of access. Unlike
the intrinsic identifier, the virtual identifier may be used for
classifying the target device in operations 440 through 460. The
intrinsic identifier may corresponds to long data of a byte scale,
including a product model name, a serial number of product, manufacturer
information, and the like, whereas the virtual identifier may correspond
to short data corresponding to 3 to 4 bits.

[0104] In operation 440, the source device generates charging power, and
transmits the charging power to the plurality of target devices using the
magnetic coupling. For example, in operation 440, the source device may
generate the charging power by adjusting a signal level of the DC voltage
to be supplied to the power amplifier 220, that is, to be input to the
power amplifier 220 based on the number of the plurality of target
devices. In operation 440, the source device may transmit the charging
power to the target device 1 and the target device 2. The DC voltage to
be supplied to the power amplifier 220 may refer to the input voltage of
the power amplifier 220 of FIG. 2. The charging power may be constantly
transmitted during a predetermined time, and may be transmitted at a
higher power level in comparison to the communication power. For example,
the power level of the communication power may be 0.1 to 1 Watt, and the
power level of the charging power may be 1 to 20 Watt.

[0105] In operation 440, the control/communication unit 115 of the source
device may determine a signal level of the DC voltage to be input to the
power amplifier 220, based on the product type of the corresponding
target device, the manufacturer information of the corresponding target
device, the product model name of the corresponding target device, the
battery type of the corresponding target device, the charging scheme of
the corresponding target device, the impedance value of the load of the
corresponding target device, the information about the characteristic of
the target resonator of the corresponding target device, the information
about the used frequency band of the corresponding target device, or the
amount of the power to be used for the corresponding target device. For
example, the source device may determine the level of the DC voltage
input to the power amplifier 220 to be a predetermined value, based on a
battery type of the target device 1 and a battery type of the target
device 2. The source device may refer to a look-up table mapped to
information of a target device, and may determine the level of the DC
voltage input to the power amplifier 220 to be the predetermined value,
for instance.

[0106] In operation 450, the source device adjusts the reference resonance
frequency FRef, based on a reflected wave of the charging power and
a transmission efficiency of the charging power. Operation 450 performed
by the source device may include operations 551 through 557 illustrated
in FIG. 5, for instance.

[0107] In operation 460, the source device transmits the charging power
using the adjusted resonance frequency.

[0108] In FIG. 4, the charging power in operation 440 may be referred to
as a first charging power, and the charging power in operation 460 may be
referred to as a second charging power. Accordingly, a power receiving
method of a wireless power receiver may include receiving the first
charging power from a wireless power transmitter, and receiving the
second charging power generated using an adjusted resonance frequency
after the reference resonance frequency FRef is adjusted in the
wireless power transmitter. Also, the reference resonance frequency
FRef may be adjusted based on a reflected wave of the first charging
power, an amount of the first charging power, or a transmission
efficiency of the first charging power. In operation 450, the wireless
power receiver may continuously perform a) receiving the second charging
power, b) receiving, from the wireless power transmitter, a command to
request an input voltage value and an input current value of a target
device, or a command to request a DC/DC output voltage value and a DC/DC
output current value of the target device, and c) transmitting, to the
wireless power transmitter, an input voltage value and an input current
value of a rectification unit, or the DC/DC output voltage value and the
DC/DC output current value.

[0110] Referring to FIG. 5, in operation 551, a source device calculates a
VSWR based on a voltage level of a reflected wave, and a level of an
output voltage and a level of an output current of a source resonator.

[0111] In operation 553, the source device determines whether the
calculated VSWR is less than a predetermined value. When the VSWR is less
than the predetermined value, the source device determines a tracking
frequency FBest having the best or highest power transmission
efficiency, among N predetermined tracking frequencies, in operation 555.
In operation 555, the tracking frequency FBest may be determined by
continuously performing operations 610 through 660 of FIG. 6. A process
of determining the tracking frequency FBest among the N
predetermined tracking frequencies may be performed by continuously
performing the operations 610 through 660, in some instances.

[0112] In operation 557, the source device generates a charging power used
for charging, using the tracking frequency FBest. The source device
may change a frequency of a switching pulse signal from a reference
resonance frequency FRef to the tracking frequency FBest.

[0113] FIG. 6 illustrates a method of selecting the tracking frequency
FBest having the best, highest, or most optimal power transmission
efficiency illustrated in FIG. 5.

[0114] Operations 610 through 660 of FIG. 6 may be performed by the
control/communication unit 115 of FIG. 1 or FIG. 2, in some instances.

[0115] Referring to FIG. 6, in operation 610, a source device selects one
of N tracking frequencies based on a predetermined frequency selection
scheme. For example, the predetermined frequency selection method may be
one of schemes illustrated in FIGS. 7A through 7C.

[0117] In operation 630, the source device transmits a charging power used
for charging. In this instance, a frequency of the transmitted charging
power may correspond to the selected tracking frequency FSelected.

[0118] In operation 640, the source device requests information from
target devices. For example, the source device may transmit, to the
plurality of target devices, a command to request an input voltage value
and an input current value of a target device, or a command to request a
DC/DC output voltage value and a DC/DC output current value of the target
device.

[0119] In operations 641 and 643, the source device receives, from each of
the plurality of target devices, an input voltage value and an input
current value of a rectification unit, or the DC/DC output voltage value
and the DC/DC output current value.

[0120] In operation 650, the source device calculates an amount of power
received by each of the plurality of target devices, based on the input
voltage value and the input current value, or the DC/DC output voltage
value and the DC/DC output current value. Since power equals current
multiplied by voltage, the amount of the received power may be easily
calculated.

[0121] In operation 660, the source device calculates a transmission
efficiency of the charging power, based on a level of an output voltage
and a level of an output current of a source resonator, and the amount of
the power received by each of the plurality of target devices. The level
of the output voltage and the output current of the source resonator may
correspond to a level of the input voltage of the power amplifier 220
illustrated in FIG. 2, and a level of a current flowing into the power
amplifier 200. Also, the level of the output voltage and the output
current of the source resonator may correspond to a level of an output
voltage and a level of an output current of the power converter 114 of
FIG. 1. The power transmission efficiency may be calculated based on the
sum of amounts of the power received by each of the target devices, and a
ratio of a level of an output power of the source resonator. The level of
the output power of the source resonator may correspond to a value
obtained by multiplying a level of an output voltage and a level of an
output current of the source resonator.

[0123] FIG. 7A illustrates a scheme of selecting tracking frequencies in a
sequential order, starting from a low frequency to a high frequency among
N predetermined tracking frequencies.

[0124]FIG. 7B illustrates a scheme of selecting tracking frequencies in a
sequential order, starting from a high frequency to a low frequency among
N predetermined tracking frequencies.

[0125] FIG. 7C illustrates a scheme of sequentially selecting M
predetermined tracking frequencies from N predetermined tracking
frequencies, primarily performing operations 620 through 660 of FIG. 6
continuously for each of the M predetermined tracking frequencies, and
secondarily performing the operations 620 through 660 continuously for
each tracking frequency, excluding the M predetermined tracking
frequencies from the N predetermined tracking frequencies, where M may be
less than N. In the scheme illustrated in FIG. 7C, a source device may
select F3 and F8, and may perform the operations 620 through 660
continuously for F3 and F8. Then, the source device may perform the
operations 620 through 660 continuously for F1, F2, F4, F5, F6, F7, F9,
F10, and F11 through FN, excluding F3 and F8.

[0126] The source device may employ a scheme of classifying N
predetermined tracking frequencies into M groups, for example, a first
group 710 and a second group 720, selecting one of the M groups based on
a number of a plurality of target devices, and sequentially selecting
tracking frequencies included in the selected group, where M may be less
than N. For example, when the number of target devices is set to less
than 4, the source device may select the first group 710, and may
performing the operations 620 through 660 continuously for F1, F2, F3,
F4, and F5 included in the first group 710.

[0127] In a wireless power transmission and charging system, the loss of
transmission power may be reduced by controlling a resonance frequency,
without a separate matching circuit.

[0128] In a wireless power transmission and charging system, the resonance
frequency may be controlled based on the power transmission efficiency.

[0129] In one or more embodiments, the source resonator, a repeater
resonator, and/or the target resonator may be configured as a helix coil
structured resonator, a spiral coil structured resonator, a
meta-structured resonator, or the like.

[0130] An electromagnetic characteristic of many materials found in nature
is that they have a unique magnetic permeability or a unique
permittivity. Most materials typically have a positive magnetic
permeability or a positive permittivity. Thus, for these materials, a
right hand rule may be applied to an electric field, a magnetic field,
and a pointing vector and thus, the corresponding materials may be
referred to as right handed materials (RHMs).

[0131] On the other hand, a material having a magnetic permeability or a
permittivity which is not ordinarily found in nature or is
artificially-designed (or man-made) may be referred to herein as a
"metamaterial." Metamaterials may be classified into an epsilon negative
(ENG) material, a mu negative (MNG) material, a double negative (DNG)
material, a negative refractive index (NRI) material, a left-handed (LH)
material, and the like, based on a sign of the corresponding permittivity
or magnetic permeability.

[0132] The magnetic permeability may indicate a ratio between a magnetic
flux density occurring with respect to a given magnetic field in a
corresponding material and a magnetic flux density occurring with respect
to the given magnetic field in a vacuum state. The permittivity indicates
a ratio between an electric flux density occurring with respect to a
given electric field in a corresponding material and an electric flux
density occurring with respect to the given electric field in a vacuum
state. The magnetic permeability and the permittivity, in some
embodiments, may be used to determine a propagation constant of a
corresponding material in a given frequency or a given wavelength. An
electromagnetic characteristic of the corresponding material may be
determined based on the magnetic permeability and the permittivity.
According to an aspect, the metamaterial may be easily disposed in a
resonance state without significant material size changes. This may be
practical for a relatively large wavelength area or a relatively low
frequency area.

[0133] FIGS. 8 through FIG. 14 illustrate various resonator structures
which may be used in one or more embodiments.

[0135] As shown, the resonator 800 having the 2D structure includes a
transmission line, a capacitor 820, a matcher 830, and conductors 841 and
842. The transmission line may include, for instance, a first signal
conducting portion 811, a second signal conducting portion 812, and a
ground conducting portion 813.

[0136] The capacitor 820 may be inserted or otherwise positioned in series
between the first signal conducting portion 811 and the second signal
conducting portion 812 so that an electric field may be confined within
the capacitor 820. In various implementations, the transmission line may
include at least one conductor in an upper portion of the transmission
line, and may also include at least one conductor in a lower portion of
the transmission line. Current may flow through the at least one
conductor disposed in the upper portion of the transmission line and the
at least one conductor disposed in the lower portion of the transmission
may be electrically grounded.

[0137] As shown in FIG. 8, the resonator 800 may be configured to have a
generally 2D structure. The transmission line includes the first signal
conducting portion 811 and the second signal conducting portion 812 in
the upper portion of the transmission line, and includes the ground
conducting portion 813 in the lower portion of the transmission line. As
shown, the first signal conducting portion 811 and the second signal
conducting portion 812 may be disposed to face the ground conducting
portion 813 with current flowing through the first signal conducting
portion 811 and the second signal conducting portion 812.

[0138] In some implementations, one end of the first signal conducting
portion 811 may be electrically connected (i.e., shorted) to a conductor
842, and another end of the first signal conducting portion 811 may be
connected to the capacitor 820. And one end of the second signal
conducting portion 812 may be shorted to the conductor 841, and another
end of the second signal conducting portion 812 may be connected to the
capacitor 820. Accordingly, the first signal conducting portion 811, the
second signal conducting portion 812, the ground conducting portion 813,
and the conductors 841 and 842 may be connected to each other such that
the resonator 800 may have an electrically closed-loop structure. The
term "closed-loop structure" as used herein, may include a polygonal
structure, for example, a circular structure, a rectangular structure, or
the like that is a circuit that is electrically closed.

[0139] The capacitor 820 may be inserted into an intermediate portion of
the transmission line. For example, the capacitor 820 may be inserted
into a space between the first signal conducting portion 811 and the
second signal conducting portion 812. The capacitor 820 may be
configured, in some instances, as a lumped element, a distributed
element, or the like. In one implementation, a distributed capacitor may
be configured as a distributed element and may include zigzagged
conductor lines and a dielectric material having a relatively high
permittivity between the zigzagged conductor lines.

[0140] When the capacitor 820 is inserted into the transmission line, the
resonator 800 may have a property of a metamaterial, as discussed above.
For example, the resonator 800 may have a negative magnetic permeability
due to the capacitance of the capacitor 820. If so, the resonator 800 may
also be referred to as a mu negative (MNG) resonator. Various criteria
may be applied to determine the capacitance of the capacitor 820. For
example, the various criteria for enabling the resonator 800 to have the
characteristic of the metamaterial may include one or more of the
following: a criterion for enabling the resonator 800 to have a negative
magnetic permeability in a target frequency, a criterion for enabling the
resonator 800 to have a zeroth order resonance characteristic in the
target frequency, or the like. The resonator 800, also referred to as the
MNG resonator 800, may also have a zeroth order resonance characteristic
(i.e., having, as a resonance frequency, a frequency when a propagation
constant is "0"). If the resonator 800 has the zeroth order resonance
characteristic, the resonance frequency may be independent with respect
to a physical size of the MNG resonator 800. Moreover, by appropriately
designing the capacitor 820, the MNG resonator 800 may sufficiently
change the resonance frequency without significantly changing the
physical size of the MNG resonator 800.

[0141] In a near field, for instance, the electric field may be
concentrated on the capacitor 820 inserted into the transmission line.
Accordingly, due to the capacitor 820, the magnetic field may become
dominant in the near field. In one or more embodiments, the MNG resonator
800 may have a relatively high Q-factor using the capacitor 820 of the
lumped element. Thus, it may be possible to enhance power transmission
efficiency. For example, the Q-factor indicates a level of an ohmic loss
or a ratio of a reactance with respect to a resistance in the wireless
power transmission. The efficiency of the wireless power transmission may
increase according to an increase in the Q-factor.

[0142] The MNG resonator 800 may include a matcher 830 for
impedance-matching. For example, the matcher 830 may be configured to
appropriately determine and adjust the strength of a magnetic field of
the MNG resonator 800. Depending on the configuration, current may flow
in the MNG resonator 800 via a connector, or may flow out from the MNG
resonator 800 via the connector. The connector may be connected to the
ground conducting portion 813 or the matcher 830. A physical connection
may be formed between the connector and the ground conducting portion
813, or between the connector and the matcher 830. In some instances, the
power may be transferred through coupling without using a physical
connection between the connector and the ground conducting portion 813 or
the matcher 830.

[0143] As shown in FIG. 8, the matcher 830 may be positioned within the
loop formed by the loop structure of the resonator 800. The matcher 830
may adjust the impedance of the resonator 800 by changing the physical
shape of the matcher 830. For example, the matcher 830 includes the
conductor 831 for the impedance-matching positioned in a location that is
separate from the ground conducting portion 813 by a distance h. The
impedance of the resonator 800 may be changed by adjusting the distance
h.

[0144] In some instances, a controller may be provided that is configured
to control the matcher 830 which generates and transmits a control signal
to the matcher 830 directing the matcher to change its physical shape so
that the impedance of the resonator may be adjusted. For example, the
distance h between a conductor 831 of the matcher 830 and the ground
conducting portion 813 may increase or decrease based on the control
signal. As shown in FIG. 8, the matcher 830 may be configured as a
passive element such as the conductor 831, for example. Of course, in
other embodiments, the matcher 830 may be configured as an active element
such as a diode, a transistor, or the like. If the active element is
included in the matcher 830, the active element may be driven based on
the control signal generated by the controller, and the impedance of the
resonator 800 may be adjusted based on the control signal. For example,
when the active elements is a diode included in the matcher 830, the
impedance of the resonator 800 may be adjusted depending on whether the
diode is in an on state or in an off state.

[0145] In some instances, a magnetic core may be further provided to pass
through the MNG resonator 800. The magnetic core may perform a function
of increasing a power transmission distance.

[0146] FIG. 9 illustrates an example of a resonator 900 having a
three-dimensional (3D) structure.

[0147] Referring to FIG. 9, the resonator 900 having the 3D structure
includes a transmission line and a capacitor 920. The transmission line
includes a first signal conducting portion 911, a second signal
conducting portion 912, and a ground conducting portion 913. The
capacitor 920 may be inserted, for instance, in series between the first
signal conducting portion 911 and the second signal conducting portion
912 of the transmission line such that an electric field may be confined
within the capacitor 920.

[0148] As shown in FIG. 9, the resonator 900 may have a generally 3D
structure. The transmission line includes the first signal conducting
portion 911 and the second signal conducting portion 912 in an upper
portion of the resonator 900, and includes the ground conducting portion
913 in a lower portion of the resonator 900. The first signal conducting
portion 911 and the second signal conducting portion 912 may be disposed
to face the ground conducting portion 913. In this arrangement, current
may flow in an x direction through the first signal conducting portion
911 and the second signal conducting portion 912. Due to the current, a
magnetic field H(W) may be formed in a -y direction. However, it will be
appreciated that the magnetic field H(W) might also be formed in the
opposite direction (e.g., a +y direction) in other implementations.

[0149] In one or more embodiments, one end of the first signal conducting
portion 911 may be electrically connected (i.e., shorted) to a conductor
942, and another end of the first signal conducting portion 911 may be
connected to the capacitor 920. One end of the second signal conducting
portion 912 may be shorted to the conductor 941, and another end of the
second signal conducting portion 912 may be connected to the capacitor
920. Accordingly, the first signal conducting portion 911, the second
signal conducting portion 912, the ground conducting portion 913, and the
conductors 941 and 942 may be connected to each other, whereby the
resonator 900 may have an electrically closed-loop structure. As shown in
FIG. 9, the capacitor 920 may be inserted or otherwise positioned into a
space between the first signal conducting portion 911 and the second
signal conducting portion 912. For example, the capacitor 920 may be
inserted into a space between the first signal conducting portion 911 and
the second signal conducting portion 912. The capacitor 920 may include,
for example, a lumped element, a distributed element, and the like. In
one implementation, a distributed capacitor having the shape of the
distributed element may include zigzagged conductor lines and a
dielectric material having a relatively high permittivity positioned
between the zigzagged conductor lines.

[0150] When the capacitor 920 is inserted into the transmission line, the
resonator 900 may have a property of a metamaterial, in some instances,
as discussed above. For example, when the capacitor is configured as a
lumped element, the resonator 900 may have the characteristic of the
metamaterial. When the resonator 900 has a negative magnetic permeability
in a predetermined frequency band by appropriately adjusting the
capacitance of the capacitor 920, the resonator 900 may also be referred
to as an MNG resonator. Various criteria may be applied to determine the
capacitance of the capacitor 920. For example, the various criteria may
include one or more of the following: a criterion for enabling the
resonator 900 to have the characteristic of the metamaterial, a criterion
for enabling the resonator 900 to have a negative magnetic permeability
in a target frequency, a criterion for enabling the resonator 900 to have
a zeroth order resonance characteristic in the target frequency, or the
like. Based on at least one criterion among the aforementioned criteria,
the capacitance of the capacitor 920 may be determined.

[0151] The resonator 900, also referred to as the MNG resonator 900, may
have a zeroth order resonance characteristic (i.e., having, as a
resonance frequency, a frequency when a propagation constant is "0"). If
the resonator 900 has a zeroth order resonance characteristic, the
resonance frequency may be independent with respect to a physical size of
the MNG resonator 900. Thus, by appropriately designing the capacitor
920, the MNG resonator 900 may sufficiently change the resonance
frequency without significantly changing the physical size of the MNG
resonator 900.

[0152] Referring to the MNG resonator 900 of FIG. 9, in a near field, the
electric field may be concentrated on the capacitor 920 inserted into the
transmission line. Accordingly, due to the capacitor 920, the magnetic
field may become dominant in the near field. Since the MNG resonator 900
having the zeroth order resonance characteristic may have characteristics
similar to a magnetic dipole, the magnetic field may become dominant in
the near field. A relatively small amount of the electric field formed
due to the insertion of the capacitor 920 may be concentrated on the
capacitor 920 and thus, the magnetic field may become further dominant.
The MNG resonator 900 may have a relatively high Q-factor using the
capacitor 920 of the lumped element and thus, it may be possible to
enhance an efficiency of power transmission.

[0153] Also, the MNG resonator 900 includes a matcher 930 for
impedance-matching. The matcher 930 may be configured to appropriately
adjust the strength of magnetic field of the MNG resonator 900. The
impedance of the MNG resonator 900 may be determined by the matcher 930.
In one or more embodiments, current may flow in the MNG resonator 900 via
a connector 940, or may flow out from the MNG resonator 900 via the
connector 940. And the connector 940 may be connected to the ground
conducting portion 913 or the matcher 930.

[0154] As shown in FIG. 9, the matcher 930 may be positioned within the
loop formed by the loop structure of the resonator 900. The matcher 930
may be configured to adjust the impedance of the resonator 900 by
changing the physical shape of the matcher 930. For example, the matcher
930 includes the conductor 931 for the impedance-matching in a location
separate from the ground conducting portion 913 by a distance h. The
impedance of the resonator 900 may be changed by adjusting the distance
h.

[0155] In some implementations, a controller may be provided to control
the matcher 930. In this case, the matcher 930 may change the physical
shape of the matcher 930 based on a control signal generated by the
controller. For example, the distance h between the conductor 931 of the
matcher 930 and the ground conducting portion 913 may increase or
decrease based on the control signal. Accordingly, the physical shape of
the matcher 930 may be changed such that the impedance of the resonator
900 may be adjusted. The distance h between the conductor 931 of the
matcher 930 and the ground conducting portion 913 may be adjusted using a
variety of schemes. For example, one or more conductors may be included
in the matcher 930 and the distance h may be adjusted by adaptively
activating one of the conductors. Alternatively or additionally, the
distance h may be adjusted by adjusting the physical location of the
conductor 931 up and down. For instance, the distance h may be controlled
based on the control signal of the controller. The controller may
generate the control signal using various factors. As shown in FIG. 9,
the matcher 930 may be configured as a passive element such as the
conductor 931, for instance. Of course, in other embodiments, the matcher
930 may be configured as an active element such as a diode, a transistor,
or the like. If the active element is included in the matcher 930, the
active element may be driven based on the control signal generated by the
controller, and the impedance of the resonator 900 may be adjusted based
on the control signal. For example, 5'' if the active element is a diode
included in the matcher 930, the impedance of the resonator 900 may be
adjusted depending on whether the diode is in an ON state or in an OFF
state.

[0156] In some implementations, a magnetic core may be further provided to
pass through the resonator 900 configured as the MNG resonator. The
magnetic core may increase the power transmission distance.

[0157] FIG. 10 illustrates a resonator 1000 for a wireless power
transmission configured as a bulky type.

[0158] As used herein, the term "bulky type" may refer to a seamless
connection connecting at least two parts in an integrated form.

[0159] Referring to FIG. 10, a first signal conducting portion 1011 and a
conductor 1042 may be integrally formed instead of being separately
manufactured and thereby be connected to each other. Similarly, the
second signal conducting portion 1012 and a conductor 1041 may also be
integrally manufactured.

[0160] When the second signal conducting portion 1012 and the conductor
1041 are separately manufactured and then are connected to each other, a
loss of conduction may occur due to a seam 1050. Accordingly, the second
signal conducting portion 1012 and the conductor 1041 may be connected to
each other without using a separate seam (i.e., seamlessly connected to
each other). Accordingly, it may be possible to decrease a conductor loss
caused by the seam 1050. Similarly, the second signal conducting portion
1012 and a ground conducting portion 1013 may be seamlessly and
integrally manufactured. In addition, the first signal conducting portion
1011 and the ground conducting portion 1013 may be seamlessly and
integrally manufactured. And, the first signal conducting portion 1011
and the conductor 1042 may be seamlessly manufactured. Also, the
conductor 1042 and the ground conducting portion 1013 may be seamlessly
manufactured.

[0161] A matcher 1030 may be provided that is similarly constructed as
described herein in one or more embodiments. FIG. 11 illustrates a
resonator 1100 for a wireless power transmission, configured as a hollow
type.

[0162] Referring to FIG. 11, each of a first signal conducting portion
1111, a second signal conducting portion 1112, a ground conducting
portion 1113, and conductors 1141 and 1142 of the resonator 1100
configured as the hollow type structure. As used herein the term "hollow
type" refers to a configuration that includes an empty space inside.

[0163] For a given resonance frequency, an active current may be modeled
to flow in only a portion of the first signal conducting portion 1111
instead of all of the first signal conducting portion 1111, the second
signal conducting portion 1112 instead of all of the second signal
conducting portion 1112, the ground conducting portion 1113 instead of
all of the ground conducting portion 1113, and the conductors 1141 and
1142 instead of all of the conductors 1141 and 1142. When a depth of each
of the first signal conducting portion 1111, the second signal conducting
portion 1112, the ground conducting portion 1113, and the conductors 1141
and 1142 is significantly deeper than a corresponding skin depth in the
given resonance frequency, it may be ineffective. The significantly
deeper depth may, however, increase the weight or manufacturing costs of
the resonator 1100, in some instances.

[0164] Accordingly, for the given resonance frequency, the depth of each
of the first signal conducting portion 1111, the second signal conducting
portion 1112, the ground conducting portion 1113, and the conductors 1141
and 1142 may be appropriately determined based on the corresponding skin
depth of each of the first signal conducting portion 1111, the second
signal conducting portion 1112, the ground conducting portion 1113, and
the conductors 1141 and 1142. When one or more of the first signal
conducting portion 1111, the second signal conducting portion 1112, the
ground conducting portion 1113, and the conductors 1141 and 1142 have an
appropriate depth deeper than a corresponding skin depth, the resonator
1100 may become lighter, and the manufacturing costs of the resonator
1100 may also decrease.

[0165] For example, as shown in FIG. 11, the depth of the second signal
conducting portion 1112 (as further illustrated in the enlarged view
region 1160 indicated by a circle) may be determined as "d" mm and d may
be determined according to

d = 1 π f μ σ . ##EQU00004##

Here, f denotes a frequency, μ denotes a magnetic permeability, and
σ denotes a conductor constant. In one implementation, when the
first signal conducting portion 1111, the second signal conducting
portion 1112, the ground conducting portion 1113, and the conductors 1141
and 1142 are made of a copper and they may have a conductivity of
5.8×107 siemens per meter (Sm-1), the skin depth may be
about 0.6 mm with respect to 10 kHz of the resonance frequency and the
skin depth may be about 0.006 mm with respect to 100 MHz of the resonance
frequency.

[0166] A capacitor 1120 and a matcher 1130 may be provided that are
similarly constructed as described herein in one or more embodiments.

[0167] FIG. 12 illustrates a resonator 1200 for a wireless power
transmission using a parallel-sheet.

[0168] Referring to FIG. 12, the parallel-sheet may be applicable to a
first signal conducting portion 1211 and a second signal conducting
portion 1212 included in the resonator 1200.

[0169] The first signal conducting portion 1211 and/or the second signal
conducting portion 1212 may not be perfect conductors and thus, may have
an inherent resistance. Due to this resistance, an ohmic loss may occur.
The ohmic loss may decrease a Q-factor and also decrease a coupling
effect.

[0170] By applying the parallel-sheet to each of the first signal
conducting portion 1211 and the second signal conducting portion 1212, it
may be possible to decrease the ohmic loss, and to increase the Q-factor
and the coupling effect. Referring to the enlarged view portion 1270
(indicated by a circle), when the parallel-sheet is applied, each of the
first signal conducting portion 1211 and the second signal conducting
portion 1212 includes a plurality of conductor lines. The plurality of
conductor lines may be disposed in parallel, and may be electrically
connected (i.e., shorted) at an end portion of each of the first signal
conducting portion 1211 and the second signal conducting portion 1212.

[0171] As described above, when the parallel-sheet is applied to one or
both of the first signal conducting portion 1211 and the second signal
conducting portion 1212, the plurality of conductor lines may be disposed
in parallel. Accordingly, the sum of resistances having the conductor
lines may decrease. Consequently, the resistance loss may decrease, and
the Q-factor and the coupling effect may increase.

[0172] A capacitor 1220 and a matcher 1230 positioned on the ground
conducting portion 1213 may be provided that are similarly constructed as
described herein in one or more embodiments.

[0173] FIG. 13 illustrates a resonator 1300 for a wireless power
transmission, including a distributed capacitor.

[0174] Referring to FIG. 13, a capacitor 1320 included in the resonator
1300 is configured for the wireless power transmission. A capacitor used
as a lumped element may have a relatively high equivalent series
resistance (ESR). A variety of schemes have been proposed to decrease the
ESR contained in the capacitor of the lumped element. According to an
embodiment, by using the capacitor 1320 as a distributed element, it may
be possible to decrease the ESR. As will be appreciated, a loss caused by
the ESR may decrease a Q-factor and a coupling effect.

[0175] As shown in FIG. 13, the capacitor 1320 may be configured as a
conductive line having the zigzagged structure.

[0176] By employing the capacitor 1320 as the distributed element, it may
be possible to decrease the loss occurring due to the ESR in some
instances. In addition, by disposing a plurality of capacitors as lumped
elements, it may be possible to decrease the loss occurring due to the
ESR. Since a resistance of the capacitors as the lumped elements
decreases through a parallel connection, active resistances of
parallel-connected capacitors as the lumped elements may also decrease
such that the loss occurring due to the ESR may decrease. For example, by
employing ten capacitors of 1 pF each instead of using a single capacitor
of 10 pF, it may be possible to decrease the loss occurring due to the
ESR.

[0177]FIG. 14A illustrates one embodiment of the matcher 830 used in the
resonator 800 provided in the 2D structure of FIG. 8, and FIG. 14B
illustrates an example of the matcher 930 used in the resonator 900
provided in the 3D structure of FIG. 9.

[0178]FIG. 14A illustrates a portion of the 2D resonator including the
matcher 830, and FIG. 14B illustrates a portion of the 3D resonator of
FIG. 9 including the matcher 930.

[0179] Referring to FIG. 14A, the matcher 830 includes the conductor 831,
a conductor 832, and a conductor 833. The conductors 832 and 833 may be
connected to the ground conducting portion 813 and the conductor 831. The
impedance of the 2D resonator may be determined based on a distance h
between the conductor 831 and the ground conducting portion 813. The
distance h between the conductor 831 and the ground conducting portion
813 may be controlled by the controller. The distance h between the
conductor 831 and the ground conducting portion 813 may be adjusted using
a variety of schemes. For example, the variety of schemes may include one
or more of the following: a scheme of adjusting the distance h by
adaptively activating one of the conductors 831, 832, and 833, a scheme
of adjusting the physical location of the conductor 831 up and down,
and/or the like.

[0180] Referring to FIG. 14B, the matcher 930 includes the conductor 931,
a conductor 932, a conductor 933 and conductors 941 and 942. The
conductors 932 and 933 may be connected to the ground conducting portion
913 and the conductor 931. The impedance of the 3D resonator may be
determined based on a distance h between the conductor 931 and the ground
conducting portion 913. The distance h between the conductor 931 and the
ground conducting portion 913 may be controlled by the controller, for
example. Similar to the matcher 830 included in the 2D structured
resonator, in the matcher 930 included in the 3D structured resonator,
the distance h between the conductor 931 and the ground conducting
portion 913 may be adjusted using a variety of schemes. For example, the
variety of schemes may include one or more of the following: a scheme of
adjusting the distance h by adaptively activating one of the conductors
931, 932, and 933, a scheme of adjusting the physical location of the
conductor 931 up and down, and the like.

[0181] In some implementations, the matcher may include an active element.
Thus, a scheme of adjusting an impedance of a resonator using the active
element may be similar as described above. For example, the impedance of
the resonator may be adjusted by changing a path of current flowing
through the matcher using the active element.

[0182]FIG. 15 illustrates one equivalent circuit of the resonator 800 for
the wireless power transmission of FIG. 8.

[0183] The resonator 800 of FIG. 8 used in wireless power transmission may
be modeled to the equivalent circuit of FIG. 15. In the equivalent
circuit depicted in FIG. 15, LR denotes an inductance of the power
transmission line, CL denotes the capacitor 820 that is inserted in
a form of a lumped element in the middle of the power transmission line,
and CR denotes a capacitance between the power transmissions and/or
ground of FIG. 8.

[0184] In some instances, the resonator 800 may have a zeroth resonance
characteristic. For example, when a propagation constant is "0", the
resonator 800 may be assumed to have ωMZR as a resonance
frequency. The resonance frequency ωMZR may be expressed by
Equation 4.

ω MZR = 1 L R C L [ Equation 4 ]
##EQU00005##

[0185] In Equation 4, MZR denotes a Mu zero resonator.

[0186] Referring to Equation 4, the resonance frequency ωMZRof
the resonator 800 may be determined by LR/CL. A physical size
of the resonator 800 and the resonance frequency ωMZR may be
independent with respect to each other. Since the physical sizes are
independent with respect to each other, the physical size of the
resonator 800 may be sufficiently reduced.

[0187] FIG. 16 illustrates an electric vehicle charging system.

[0188] Referring to FIG. 16, an electric vehicle charging system 1600
includes a source system 1610, a source resonator 1620, a target
resonator 1630, a target system 1640, and an electric vehicle battery
1650.

[0189] The electric vehicle charging system 1600 may have a similar
structure to the wireless power transmission system of FIG. 1. The source
system 1610 and the source resonator 1620 in the electric vehicle
charging system 1600 may function as a source. Additionally, the target
resonator 1630 and the target system 1640 in the electric vehicle
charging system 1600 may function as a target.

[0190] The source system 1610 may include a variable SMPS, a power
amplifier, a matching network, a controller, and a communication unit,
similarly to the source 110 of FIG. 1. The target system 1640 may include
a matching network, a rectification unit, a DC/DC converter, a
communication unit, and a controller, similarly to the target 120 of FIG.
1.

[0191] The electric vehicle battery 1650 may be charged by the target
system 1640.

[0192] The electric vehicle charging system 1600 may use a resonant
frequency in a band of a few kilohertz (KHz) to tens of MHz.

[0193] The source system 1610 may generate power, based on a type of
charging vehicle, a capacity of a battery, and a charging state of a
battery, and may supply the generated power to the target system 1640.

[0194] The source system 1610 may control the source resonator 1620 and
the target resonator 1630 to be aligned. For example, when the source
resonator 1620 and the target resonator 1630 are not aligned, the
controller of the source system 1610 may transmit a message to the target
system 1640, and may control alignment between the source resonator 1620
and the target resonator 1630.

[0195] For example, when the target resonator 1630 is not located in a
position enabling maximum magnetic resonance, the source resonator 1620
and the target resonator 1630 may not be aligned. When a vehicle does not
stop accurately, the source system 1610 may induce a position of the
vehicle to be adjusted, and may control the source resonator 1620 and the
target resonator 1630 to be aligned.

[0196] The source system 1610 and the target system 1640 may transmit or
receive an ID of a vehicle, or may exchange various messages, through
communication.

[0197] The descriptions of FIGS. 2 through 15 may be applied to the
electric vehicle charging system 1600. However, the electric vehicle
charging system 1600 may use a resonant frequency in a band of a few KHz
to tens of MHz, and may transmit power that is equal to or higher than
tens of watts to charge the electric vehicle battery 1650.

[0198] The units described herein may be implemented using hardware
components, software components, or a combination thereof. For example, a
processing device may be implemented using one or more general-purpose or
special purpose computers, such as, for example, a processor, a
controller and an arithmetic logic unit, a digital signal processor, a
microcomputer, a field programmable array, a programmable logic unit, a
microprocessor or any other device capable of responding to and executing
instructions in a defined manner. The processing device may run an
operating system (OS) and one or more software applications that run on
the OS. The processing device also may access, store, manipulate,
process, and create data in response to execution of the software. For
purpose of simplicity, the description of a processing device is used as
singular; however, one skilled in the art will appreciated that a
processing device may include multiple processing elements and multiple
types of processing elements. For example, a processing device may
include multiple processors or a processor and a controller. In addition,
different processing configurations are possible, such a parallel
processors.

[0199] The software may include a computer program, a piece of code, an
instruction, or some combination thereof, for independently or
collectively instructing or configuring the processing device to operate
as desired. Software and data may be embodied permanently or temporarily
in any type of machine, component, physical or virtual equipment,
computer storage medium or device, or in a propagated signal wave capable
of providing instructions or data to or being interpreted by the
processing device. The software also may be distributed over network
coupled computer systems so that the software is stored and executed in a
distributed fashion. In particular, the software and data may be stored
by one or more computer readable recording mediums. The computer readable
recording medium may include any data storage device that can store data
which can be thereafter read by a computer system or processing device.
Examples of the computer readable recording medium include read-only
memory (ROM), random-access memory (RAM), CD-ROMs, magnetic tapes, floppy
disks, optical data storage devices. Also, functional programs, codes,
and code segments for accomplishing the example embodiments disclosed
herein can be easily construed by programmers skilled in the art to which
the embodiments pertain based on and using the flow diagrams and block
diagrams of the figures and their corresponding descriptions as provided
herein.

[0200] A number of example embodiments have been described above.
Nevertheless, it should be understood that various modifications may be
made. For example, suitable results may be achieved if the described
techniques are performed in a different order and/or if components in a
described system, architecture, device, or circuit are combined in a
different manner and/or replaced or supplemented by other components or
their equivalents. Accordingly, other implementations are within the
scope of the following claims.